In the field of special effects in motion pictures, artificial smoke or fog generators have been used for generating artificial clouds of smoke or fog. Traditionally, artificial fog was produced by spraying or atomizing pure mineral oil into the surrounding atmosphere. Another type of fog has been made by percolating high pressure air through an oil tank. Some of the historical methods of generating artificial fog are described in the book Special Effects in Motion Pictures, which is a text which discusses the subject. With respect to the above-mentioned methods of generating artificial fog, the book explains: "both methods were long since discarded by the studios, because of the heavy oil deposits which frequently ruined wardrobe articles and usually rendered sets dangerously oily and slippery."
As noted above, traditional fog producing machines generate a heavy oil deposit in the surrounding environment. The heavy oil deposit is produced because these machines generate a significant amount of relatively large oil bubbles. These machines normally use a fog nozzle immersed in a large oil bath. A strong pump is used to produce a strong stream of air that is fed to the immersed nozzle. While the nozzle is immersed in the oil bath, the stream of air bursts out of the nozzle and creates a significant amount of large and fine oil bubbles.
Recently, attempts have been made to filter out the larger oil bubbles and allow only the finer oil bubbles to be emitted from these machines. Although the more recent artificial smoke generators produce somewhat finer oil bubbles, these machines are still very large, inefficient, and costly to rent and maintain.
Even the very recent models of artificial smoke generators which have been commercially available are normally transported in a truck. Delivery or other transportation costs significantly add to the cost of renting the machines. In addition, these large machines consume substantial quantities of power when in operation, because a large air compressor is normally used for feeding a strong stream of air into the fog nozzle. Further, the rental fee is relatively high due to the high maintenance cost, size and complexity of the machines.
In addition most of these machines require maintenance by both the user and vendor. For example, the user is normally required to change some of the oil filters inside the machine.
Accordingly, the principal object of the present invention is to provide a small, efficient, inexpensive and maintenance-free artificial fog generator that produces very fine oil bubbles.